1. Field
The presently disclosed subject matter relates to semiconductor light-emitting devices in which light emitted from a semiconductor light-emitting chip is wavelength-converted by a wavelength converting layer, and more particularly, the disclosed subject matter relates to semiconductor light-emitting devices for a vehicle light and the like, which can emit various mixture lights having a high light-emitting efficiency and a substantially same color tone from a small light-emitting surface.
2. Description of the Related Art
Semiconductor light-emitting devices, in which a part of the light emitted from a semiconductor light-emitting chip is converted into light having a different wavelength by a phosphor and in which a mixture light comprises the light having the different wavelength mixed with the light emitted directly from the light-emitting chip is emitted, have been used as a light source for various lighting units. Such light-emitting devices have been also used as a light source for vehicle lamps such as a headlight for reasons of a battery friendly, lamp miniaturization, etc.
When the semiconductor light-emitting devices are used as a light source for a lighting unit such as a vehicle headlight, which controls light emitted from the light-emitting devices using a reflector and/or a projector lens, a light-emitting device having a small light-emitting surface may be desired to efficiently control light emitted from the light-emitting device with a small optical structure. Therefore, conventional semiconductor light-emitting devices including a wavelength material, which emit light have a white color tone from a small light-emitting surface, for example, are disclosed in Patent Document No. 1 (Japanese Patent Application Laid Open JP2010-272847).
FIG. 13 is an enlarged side cross-sectional view showing a conventional semiconductor light-emitting device having a small light-emitting surface, which is disclosed in Patent Document No. 1. The conventional semiconductor light-emitting device 1A includes: a base substrate 5 having a mounting surface, and a semiconductor light-emitting chip 2 having a top surface, a bottom surface and bottom electrodes located on the bottom surface, mounted on the mounting surface of the base substrate 5 via conductive members 6, each of the bottom electrodes electrically connected to a respective one of conductor patterns formed on the mounting surface of the base substrate 5 via a respective one of the conductive members 6.
In addition, the semiconductor light-emitting device 1A also includes: a transparent member 3 having a bottom surface 3a and a light-emitting surface 3b including a wavelength converting material, being disposed on the top surface of the semiconductor light-emitting chip 2 so as to be able to wavelength-convert light emitted from the semiconductor light-emitting chip 2, the bottom surface 3a thereof being larger than the top surface of the semiconductor light-emitting chip 2, and therefore a part of the bottom surface 3a contacting with the top surface of the semiconductor light-emitting chip 2, and the light-emitting surface 3b thereof being smaller than the bottom surface 3a: and a reflective resin layer 4 surrounding the transparent member 3 and the semiconductor light-emitting chip 2 to prevent the transparent member 3 from peeling from the semiconductor light-emitting chip 2, and being disposed between the mounting surface of the base substrate 5 and the bottom surface of the semiconductor light-emitting chip 2 so as to surround each of the conductive members 6.
Consequently, the conventional semiconductor light-emitting device 1A may emit a mixture light, in which a part of light emitted from the semiconductor light-emitting chip 2 is converted into light having a different wavelength by the wavelength converting material and the light having the different wavelength is mixed with the light emitted directly from the light-emitting chip 2, from the light-emitting surface that is smaller than the bottom surface 3a of the transparent member 3 including the wavelength converting material in terms of results.
However, the reflective resin layer 4 is also disposed underneath another part of the bottom surface 3a of the transparent member 3, which does not contact with the top surface of the semiconductor light-emitting chip 2, while contacting with a side surface of the semiconductor light-emitting chip 2. Accordingly, it may be difficult for the conventional semiconductor light-emitting device 1A to use not only the light emitted from the top surface of the semiconductor light-emitting chip 2, but also light emitted from the side surface of the semiconductor light-emitting chip 2 with high efficiency as the mixture light having a wavelength-converted wavelength, which is different from that the light emitted from the semiconductor light-emitting chip 2.
Therefore, Applicant of the disclosed subject matter discloses other conventional semiconductor light-emitting devices having a small light-emitting surface and a high light-emitting efficiency, which can use light emitted from a substantially whole light-emitting surface including a side surface of a semiconductor light-emitting chip, in Patent Document No. 2 (Japanese Patent Application Laid Open JP2013-038187) and in Patent Document No. 3 (U.S. Pat. No. 8,461,610), which are invented by the inventor of the presently disclosed subject matter and the like.
FIG. 14 is an enlarged side cross-sectional view showing another conventional semiconductor light-emitting device having a small light-emitting surface, which is disclosed in Patent Document No. 2 and No. 3. The other conventional semiconductor light-emitting device 1B includes: a base substrate 17 having a mounting surface and a peripheral portion; a frame 16 mounted on the peripheral portion of the base substrate 17; a semiconductor light-emitting chip 11 having bottom electrodes being mounted on the mounting surface of the base substrate 17 via metallic bumps 12, which electrically connects each of the bottom electrodes to a respective one of conductor patters via a respective one of the metallic bumps; and a wavelength converting layer 14 being slightly larger than a top surface of the semiconductor light-emitting chip 11, and being located over the top surface of the semiconductor light-emitting chip 11 to wavelength-converting light emitted from the semiconductor light-emitting chip 11.
In addition, the semiconductor light-emitting device 1B also includes: a transparent material layer 13 having a side surface 13S being disposed between a bottom surface of the wavelength converting layer 14 and the semiconductor light-emitting chip 11, and the side surface 13S extending from a substantially bottom end of the semiconductor light-emitting chip 11 toward a substantially bottom end of the transparent material layer 13; and a reflective material layer 15 disposed between an inner surface of the frame 16 and the wavelength converting layer 14 and the transparent material layer 13 and between the bottom surface of the semiconductor light-emitting chip 11 and the mounting surface of the base substrate 17 so as to surround each of the metallic bumps 12.
According to the conventional semiconductor light-emitting device 1B, light emitted from the semiconductor light-emitting chip 11 may widely direct toward the wavelength converting layer 14, and also light emitted from a side surface of the semiconductor light-emitting chip 11 may almost direct toward the wavelength converting layer finally by reflecting the light on the side surface 13S of the transparent material layer 13, because the side surface 13S contacts with reflective material layer 16 and is formed in a convex shape from the reflective material layer 16 toward the wavelength converting layer 14.
In addition, light directed from the semiconductor light-emitting chip 11 toward the mounting surface of the base substrate 17 may also be directed toward the wavelength converting layer 14 by using the bottom surface of the semiconductor light-emitting chip 11, which contacts with the metallic bumps 12 or the reflective material layer 16. Consequently, the conventional semiconductor light-emitting device 1B can enable most of light emitted from the light-emitting chip 11 to be directed toward the wavelength converting layer 14, and therefore can emit a mixture light having a high light-emitting efficiency from a small light-emitting surface, which is a top surface of the wavelength converting layer 14. However, the light-emitting surface of the light-emitting device 1B may be a substantially same shape as a top surface of the transparent material layer 13, and therefore may not be smaller than the top surface of the transparent material layer 13.
The above-referenced Patent Documents and an additional Patent Document are listed below and are hereby incorporated with their English specification and abstracts in their entireties.
1. Patent Document No. 1: Japanese Patent Application Laid Open JP2010-272847
2. Patent Document No. 2: Japanese Patent Application Laid Open JP2013-038187
3. Patent Document No. 3: U.S. Pat. No. 8,461,610 (ST3001-0307)
4. Patent Document No. 4: U.S. Patent Publication No. US 2012-0025218 (ST3001-0312)
5. Patent Document No. 5: U.S. Pat. No. 8,251,560 (ST3001-0242)
6. Patent Document No. 6: U.S. Patent Publication No. US 2012-0320617 (ST3001-0242CON)
The disclosed subject matter has been devised to consider the above and other problems, features, and characteristics. Thus, embodiments of the disclosed subject matter can include semiconductor light-emitting devices that can emit various mixture lights having a high light-emitting efficiency and a substantially uniform color tone from a small light-emitting surface. The disclosed subject matter can also include a semiconductor light-emitting device using a plurality of semiconductor light-emitting chips that can be used for wavelength-converting light having a very high light-emitting intensity with high light-emitting efficiency from a comparatively small light-emitting surface.